Jailbreak

Cydia

Note: This Post will be udpated as news becomes available. Please share your experiences in this thread. It is highly suggested you do not update to iOS 4 right away. Please be patient.

Today, as expected, Apple released iOS 4 to the public. But before you get too excited, there are some things you should know before updating to iOS 4. If you want to play Jailbreak with your iDevice, make sure you read through this.

iOS 4 is compatible with the 3G, 3GS, the newest iPod Touch and iPhone 4. Those of you that have played with the GM release, the build number on this public release is exactly the same; 8A293. So as for changes since the GM there are none in this release.

Update:

Originally Posted by bennyg

there are actually differences in the GM and public release. Notice no game centre in the public release? Also if you go to http://oo.apple.com to opt out of the iAd data collection stuff on the GM release it states your not on iOS4!

Jailbreaking

iPhone3GS & iPod3G owners (especially if you used Spirit for your first JB) should stay away from iOS4 for now

Wizdaz has kept the community in the know, informing us that PwnageTool is currently being updated as we speak. PwnageTool 4.0 will support the iPhone 3G (with Pwnage exploit), iPhone 3GS and iPod Touch 2G (both with 24kPwn exploit). Keep in mind this means no support for the newer bootom. Remember the tethered days? If that was you, then you will need to wait until Spirit is updated or a new tool is updated for such.

There is of course the Redsn0w option if you have a 3G, but stay away from any custom packages. The Dev-Team has written it well, and because of their credibility, here is exactly what they say

We are working hard on a release to our tools that will jailbreak your device (or give you iOS 4 via the jailbreak train) and provide you with a carrier unlock.

Until these tools are released you should hold off on updating your device until we have fully tested our tools with all the relevant devices.

If you rely on hacktivation or a carrier unlock (ultrasn0w) then you should not upgrade until we have fully tested and released our tools.

Don’t be tempted with unofficial PwnageTool/redsn0w bundles or releases, just check here or our team twitter for real time release information.

Remember, we risk our devices so you don’t have to (but this time anyone who has made a mistake upgrading their baseband firmware at 3.1.3 or 4.0 should be OK real soon Now!

The iPhone Dev Team has released ultrasn0w 0.93 for unlocking your new iOS 4. Simply add the Cydia repo: repo666.ultrasn0w.com. This version of ultrasn0w will unlock basebands 04.26.08 thru 05.13.04. If your unsure, that means that ultrasn0w unlocks ALL basebands since iPhone OS 3.1. Even more specifically, 04.26.08, 05.11.07, 05.15.01, and 05.13.04. Remember to disable 3G on T-Mobile USA.

So on the unlocking front, you're pretty much golden. However it's still recommend to wait just a little bit longer before making the plunge for iOS 4.